Expansible piston



July 21, 1925. 1,546,603

R. A. MUELLER EXPANSIBLE PISTON Filed Aug. 10, 1923 2 Sheets$heet 1 R A. N R gwvmd oz Wm m 5Q M M r J n T N.

July 21, 1925.

R. A. MUELLER EXPANS IBLE PI SI'ON Filed Aug. 10, 1923 2 Sheets-Sheet 2 Patented July 21, 1925.

UNITED STATES ROBERT A. MUELLER, OF HOUSTON, TEXAS.

EXPANSIIBLE Pis'roN.

Application filed August 10, 1923 Serial No. 656,661.

To all whom it may concern:

Be it known that I, Ronnn'r A. MUELLER, a citizen of the United States, residing at Houston, Harris County, Texas, have invented a certain new and useful Improvement in Expansible Pistons, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to pistons of the expanding type and is particularly adapted for use on pumps.

In the use of pumps .for handling mud or water laden with sand and sediment, it is an ordinary difficulty to find excessive wear in the packing means whereby a close fit is maintained between the piston and the cylinder walls.

It is an object of the invention to construct a piston having means thereon to compress the packing longitudinally and thus expand it radially to take up for wear as wear occurs.

Another object is to so construct the piston and cylinder that the packing may be expanded readily without removing the piston from the cylinder and with a minimum amount of manipulation ofthe tightening means.

Another object is to provide a piston wherein the parts making up the piston body, packing and expanding means will be held rigidly in position at all times, thus preventing play in said parts and consequent wear during the operation of the pump.

Referring to the drawing herewith, wherein like numerals of reference are applied to like parts throughout the different views, Fig. 1 is a central vertical section through a pump piston and cylinder showing my invention applied thereto; Fig. 2 is a transverse section on the plane 2-2 of Fig. 1; Fig. 3 is a broken longitudinal section through a piston showing a slightly different embodiment of the invention; Fig. 4 and Fig. 5 are transverse sections on the planes 4-4 and 5-5 respectively of Fig. 3;

Fig. 6 is a longitudinal section of a still different embodiment of my invention; Fig. 7 is an end elevation .of the Fig. 7 modification.

In Figs. 1 and 2 I have shown the invention as applied to a horizontal mud pump,

such as is commonly used in rotary drilling operations for wells. There is a housing having a central cylinder 2 fitted therein. At the forward end of said cylinder the housing is closed by a cylinder head 3, said head being secured to the housing by means of set screws4. Centrally of the cylinder head 3 is a threaded opening 5 within which is secured an elongated cap 6, furnishing a protecting housing for the end of a piston rod 7, to be presently described.

Working in the cylinder 2 is a piston 8, said piston having a tapered fit with a piston rod 7 the forward end of said piston rod extending through the body of the piston and through the opening in the cylinder head into the cap 6. The forward end of the piston head 8 is recessed, or reduced in diameter at 9 to provide a seat for a sleeve 10 of packing material. This sleeve may be of rubber, or any other similar compressible composltlon which is wear-resisting and capable of being expanded under compression longitudinally to make a close fit with the cylinder walls.

The forward end of the cylinder head is recessed centrally to provide a chamber 11, within which a nut 12, secured upon the threaded end of the piston rod, may be rotated. The said nut serves to clamp the head securely in position upon the piston rod, and is in turn locked by means of the nut 13 thereon.

The packing sleeve 10 is adapted to be compressed longitudinally by means of a compression ring 14, which has its lower end bevelled slightly in an upward direction to assist in better expanding the packing. The forward end of the compression ring is extended inwardly and has a threaded connection with ashank 15 extending forwardly therethrough, and slidable upon the forward threaded end of the piston rod 7 The base of said shank 15 is provided with a hexagonal recess, fitting closely over the locked nut 13, thereby preventing rotation of the said shank and the ring. The said shank 15 is threaded on its outer periphery by a left-hand thread, indicated at 16, the said thread being adaptedto receive the lower end of a connecting sleeve 17, which may be secured thereon by a left-hand or counterclockwise turn of said sleeve.

At the extreme forward end of the piston rod 7,- within the cap 6, is a threaded plug 18. This lug is secured on s ald piston rod with a right-hand or clockwise turn, as is customary. The outer surface is hexagonal at the forward end to provide a hold for ahwrench, and the rearward end is reduced in diameter and threaded at 19 for engagement with the forward end of the connecting sleeve 17, previously described.

In the operation ofthis device, the parts are assembled as described and shown in the drawing, and the piston is ready for operation. The reciprocation thereof in the cylinder will eventually cause wear upon the packing sleeve 10, so that the tight fit with the cylinder walls necessary to its operation will be impaired. To overcome this, it will only be necessary to remove the cap 6 and screw down upon the nut 18. This action will tend to force the threaded plug inwardly along the piston rod 7, carrying with it in its rotation the connecting sleeve 17. The said connecting sleeve will also be thereby rotated in a right-hand direction, tending to unscrew the connection between said sleeve and the threaded shank 15. Asthe forward end of the sleeve is in tight contact with the head of the threaded plug, the action will be to force the shank 15 and the ring rearwardly against the packing sleeve and compress it longitudinally, so as to force it outwardly against the cylinder walls, taking up for the wear. It will be noted that there is a double action upon the compression ring; that is, there will be a compression due to the screwing up of the threaded plug upon the piston rod, forcing the connecting sleeve and the ring rearwardly, and there will be a similar action due to the unscrewing of the shank 15 of the ring from the connecting sleeve.

In Figs. 3, 4 and 5, a slightly different embodiment of the clamping means for the expanding packing is employed. In this embodiment the piston head 8 is held upon the piston rod by means of a nut 12, as in the other embodiment, although no lock nut is used. The compression ring 14 is secured to the threaded shank 20 of a threaded plug 21, said threaded plug havingv a threaded connection both with the compression ring 14 and the threaded end 7 of the piston rod. The threaded connection with the piston rod is in the usual right-hand or clockwise direction, and the connection with the compression ring 14 is a left-hand or counterclockwise engagement, these terms being employed to indicate the screwing up of the parts with a right or left hand turn. The compression ring 14 is held against rotation relative to the piston rod by means of a dowel pin 22 fitted within a recess 23 in the piston head.

Outside the compression ring 14, and fitting slidably over the hexagonal end of the threaded plug, is a cap 24. This cap is slidable upon the threaded end of the piston rod, and is held in position against the compression ring by means'of a nut 25 threaded upon the piston rod.

In the operation of this device, when it becomes necessary to expand the packing sleeve 10, a wrench is fitted over the hexagonal outer surface of the cap 24, and the same is rotated in the usual right-hand di rection. The cap will act as a wrench to rotate the threaded plug 21, thus forcing the said threaded plug rearwardly along the piston rod, carrying with it the compression ring 14. There will also be an unscrewing action of the outer thread of the threaded plug upon the compression ring, and this will further tend to force the compression ring rearwardly to expand the packing sleev'e. There will be in this case, therefore, a double action upon the packing as the threaded plug is rotated in approximately the same general way as' was described in connection with the previous embodiment. The cap 24 will remain stationary and the threaded plug will slide forwardly relative thereto, as the packing is tightened.

In the embodiment disclosed in Figs. 6 and 7, a still further simplification of the parts has been indicated. There is a nut 12 holding the piston head firmly upon the the piston rod 7", as in the previous embodiment. The compression ring 14 is threaded upon the shank of a threaded plug 20, having a hexagonal head 21, as previously described. The compression ring is held against rotation relative to the head by a dowel pin 22. In this embodiment. however, the cap- 24 has been omitted. and the head 21 of the threaded plug is enlarged to such an extent that it may be gripped by a wrench without said wrench. engaging the lock nut 25 on the forward end of the piston rod. The threaded plug 21 in this embodiment, however. is not screwed upon the piston rod. but is slidable thereon, and has a threaded engagement at 26 with the compression ring. so that whenthe threaded plug is rotated in the right hand direction, it will tend to force the compression ring forwardly to expand the packing sleeve. The forward end of the lock nut 25 bears against the end of the threaded plug, and prevents its being forced forwardly as it is rotated within the compression ring.

The advantages of this construction are that the packing may be expanded without removing the piston from the cvlinder, and in the case of the two embodiments first described, a partial turn only of the nut upon the piston rod will be necessary to expand the packing sleeve, due to the double action obtained in rotating the same. This will make it possible to adjust and expand greater force than could be readily exerted without the double action obtained in-tightening up the compression ring. It is the further advantage that the parts making up the compression device are readily accessible'without dismantling the pump and the cylinders as is commonly required in these types of pumps. The compression of the packing ring is radially outward, due to the compression longitudinally ofthe ring, and such compression hows the sleeve outwardly, as shown in Figs. 3 and 6, so that the packing will conform to the wear also upon the inner wall of the cylinder. This is desirable where a close fit is desired in a pump somewhat worn. It is further to be n'oted that the compression ring is held rigidly in position at all times, and may not have a movement upon the piston rod during the operation of the piston.

The parts are simple and strong, and will not readily become worn or get out of order.

The further objects and advantages will be apparent to one skilled in the art without further description. What I claim as new and desire to protect by Letters Patent 1. Ina pump, a cylinder, a piston reciprocable therein, a piston rodextending through said piston and havinga threaded forward end thereon, a packing sleeve of compressible material on said piston, a compression ring bearing on said sleeve, a-

threaded' shank on said ring, a threaded plug screwed upon the vend of said piston rod, a connecting sleeve engaging said threaded plug and said shank, said connecting sleeve being screwed upon said shank with aleft hand thread whereby the rotation of said threaded plug and said sleeve in a right hand direction to advance said plug on said piston rod will compress said packing;

2. In a pump, a piston rod and piston, a

packing sleeve of compressible material thereon, a compression ring bearing on said packing sleeve at one end, a nut on the rod of said piston, a. sleeve on said nut having a threaded left handed connection with said ring whereby the screwing upon said nut will exert .a double thrust on said packing sleeve. v

3. In a pump, a piston rod,- a. piston, a packing sleeve thereon of compressible material, acompression ring on said piston bearing against the end of said packing sleeve, a left-hand-threaded shank on said ring around the rod of said piston, a connecting sleeve on said shank and means connecting said vsleeve with the threaded forward end of said piston rod whereby the rotation thereof will advance said connecting sleeve and the rotation of said connecting sleeve will also advance said compression ring in the manner'described. v

4. In a pump, a cylinder, a piston working therein, a cylinder head, a removable elongated cap secured centrallv in said cylinder head, a piston rod extending through said piston, a packing sleeve of compressible material on said piston, a compression ring at the end of said piston bearing on said packing, a shank on said compression ring, a. connecting sleeve on sa1d shank and a threaded plug screwed on said piston rod within said cap adapted to exert a double thrust on said compremion sleeve when sa1d threaded plug is rotated to expand said packing sleeve;

5. In a pump, a piston rod. a plston, a packing sleeve of compressible material thereon, a compression ring bearing on said packing sleeve at one end, a nut on the rod of said piston, a sleeve on said compression ring having a left hand thread thereon and and connected with said nut for the purpose described.

6. In a pump, a piston rod, a piston thereon, a compressible packing sleeve on said piston, a plug having threaded engagement with the forward end of said rod, a compression ring on said packing and a sleeve connecting said plug andsaid ring whereby said plug may be rotated to advance said 1%1 testimony whereof, I hereunto aflix my signature this the 4th day of August, A. D. 1923.

ROBERT A. MUELLER. 

